Accurately determining the delay along a physical link from a sender to a receiver, may be useful in many applications. For example, determining the delay from a source of an emergency call (911 in the USA, for example) to a police switchboard may be critical for emergency workers to respond effectively. In this regard, traditional circuit switched telephone networks are deterministic in that the path and delay of information over the network is known, and as a result, the source of the call may be determined. However, for a VoIP phone, determining the delay of a 911 call from source to receiver with sufficient accuracy is difficult if not impossible, using conventional technology. In this regard, obtaining accurate delay information in non-deterministic, packet switched networks (PSN), such as the Internet, is difficult due to variable delays caused by factors such as the operating system of a traversed network node, network congestion, and routing path, for example. One method conventionally used to determine delays between nodes in a network is time-domain reflectometry (TDR). However, if there are no discontinuities in the physical links, or the connections are very well matched, then TDR does not provide a very accurate measurement. Accordingly, conventional methods for determining the path delay between a source and a destination of a packet provide insufficient accuracy for many applications.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.